Every option price is pushed and pulled by a handful of forces — the stock’s moves, the calendar, and the market’s mood. The Greeks are just the gauges that measure each force, one at a time.
Answer first: the Greeks are sensitivity measures. Each one answers a single question about an option’s price: delta — how much does it move when the stock moves $1? Gamma — how fast does delta itself change? Theta — how much value melts away per day? Vega — what happens if expected volatility shifts? Rho — what about interest rates? Learn the first four and most option behavior stops being mysterious.
Delta ranges from 0 to 1 for calls and 0 to −1 for puts. A call with a 0.60 delta gains about $0.60 (per share, so $60 per contract) when the stock rises $1. Deep in-the-money options approach delta 1 and trade almost like stock; far out-of-the-money options sit near 0 and barely respond. Traders also read delta as a rough market-implied odds gauge: that 0.60-delta call is loosely priced like a ~60% chance of finishing in the money — an approximation, not a law. At-the-money options start near 0.50.
Gamma measures how much delta changes per $1 stock move. It is largest for at-the-money options close to expiration — which is why short-dated options flip character so violently: a 0.50-delta option can become a 0.80-delta option on one good day. High gamma means your exposure is unstable; every point the stock moves rewrites your position’s behavior.
Theta is the daily cost of holding an option, all else equal. An option with a theta of −0.05 loses about $5 per contract per day to time decay. Decay is not linear: it accelerates as expiration approaches, hitting at-the-money options hardest in the final weeks. Buyers pay this rent; sellers — like covered call writers and put sellers — collect it. That single sentence explains half of all options strategies.
Vega measures sensitivity to implied volatility — the market’s forecast of future movement baked into the premium. A vega of 0.10 means a one-percentage-point rise in implied volatility adds about $10 per contract, in either direction. This is why options get expensive before earnings announcements and deflate right after: the event uncertainty leaves the price even when the stock barely moves. Buying options when volatility is already elevated is paying top dollar for the mood.
Rho tracks interest-rate sensitivity. For short-dated options it is small enough that most retail traders ignore it; it matters more for long-dated options (LEAPS) when rates shift meaningfully.
| Greek | Measures response to | Typical beginner takeaway |
|---|---|---|
| Delta | $1 stock move | Your directional exposure, 0 to ±1 |
| Gamma | Delta’s own change | Biggest near the money, near expiry |
| Theta | One day passing | Buyers bleed daily; sellers collect |
| Vega | 1 pt of implied volatility | Options are dear when fear is high |
| Rho | 1 pt of interest rates | Mostly matters for LEAPS |
How they interact: a long call is positive delta, positive gamma, negative theta, positive vega — it wants the stock up, fast, before time runs out, ideally with fear rising. Every options position is just a different mix of those four exposures.
Reality check: Greeks are model outputs (usually Black-Scholes-style), recalculated constantly — they are snapshots, not promises, and they all shift together when the stock jumps. Options can lose 100% of the premium. Educational content only — not financial advice.
Put the theory to work with the options profit calculator, breakeven calculator, covered call calculator and cash-secured put calculator — or trade a simulated option in the options trading game first.
Last updated July 2, 2026 · Written by Mustafa Bilgic. Educational only — not financial advice.
Sensitivity measures for an option's price: delta (stock moves), gamma (delta's change), theta (time decay per day), vega (implied volatility changes) and rho (interest rates).
The option gains about $0.60 per share ($60 per contract) for each $1 the stock rises, and it is loosely priced like a ~60% chance of expiring in the money.
The daily loss of option value from time passing. A theta of −0.05 costs about $5 per contract per day, and decay accelerates as expiration approaches.
Implied volatility collapsed after the event — the vega effect. The volatility premium you paid deflated faster than the favorable move added value.
Delta and theta. Delta tells you your directional exposure; theta tells you what holding the position costs every day you wait.